Reprocessed uranium

Reprocessed uranium (RepU) is the uranium recovered from nuclear reprocessing, as done commercially in France, the UK and Japan and by nuclear weapons states' military plutonium production programs. This uranium actually makes up the bulk of the material separated during reprocessing. Commercial LWR spent nuclear fuel contains, on average, only four percent plutonium, minor actinides and fission products by weight.

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Reuse of reprocessed uranium has not been common because of low prices in the uranium market of recent decades, and because of the undesirable isotopic contaminants

• uranium-236 (which absorbs neutrons without fissioning and becomes neptunium-237 which is one of the most difficult isotopes for long-term disposal in a deep geological repository),
• uranium-232 (whose decay products emit strong gamma radiation making handling more difficult), and
• uranium-234 (which is fertile material but can affect reactivity differently than uranium-238).^[1]

In the last few years uranium prices have risen again, and if the price becomes high enough, it is possible that reprocessed uranium will be re-enriched and reused. A higher enrichment level will be required to compensate for the ²³⁶U which is lighter than ²³⁸U and therefore will concentrate in the enriched product. Also, if fast breeder reactors ever come into commercial use, reprocessed uranium, like depleted uranium, will be usable in their breeding blankets.

There have been some studies involving the use of reprocessed uranium in CANDU reactors. CANDU is designed to use natural uranium as fuel; the U-235 content remaining in spent PWR/BWR fuel is typically greater than that found in natural uranium, allowing the re-enrichment step to be skipped. Fuel cycle tests also have included the DUPIC (Direct Use of spent PWR fuel In CANDU) fuel cycle, where used fuel from a Pressurized Water Reactor (PWR) is packaged into a CANDU fuel bundle with only physical reprocessing (cut into pieces) but no chemical reprocessing.^[2]

References

1. ^ http://www.francenuc.org/en_mat/uranium4_e.htm Uranium from reprocessing
2. ^ DUPIC The Evolution of CANDU Fuel Cycles and Their Potential Contribution to World Peace